A common structure of a contact component (or a conductive pill) as used in a corresponding switch panel or keypad is as follows:                A metal surface layer and an elastic material (such as a rubber layer) are bonded together. Gold, silver and other precious metals have good electrical conductivity, good chemical stability and other properties, and thus they are commonly used as the contact materials. However, their expensive prices limit their applications. The chemical stability of copper, a base metal, is not as good as a precious metal. Some base metals such as nickel, titanium, iron and their alloys, including stainless steels, having a good chemical stability, are not as ideal as precious metals with respect to the use as a contact material, and their conductivities are low as compared to silver, copper and gold. However, their commercial availability is comparatively better and their prices are much less than precious metals when used as conductive materials or contact materials. There are advantages and disadvantages if either a base metal or a precious metal is used alone.        
Chinese Patent Application No. 02152226.X discloses “A Moving Contact Assembly, the Panel Switch with it, and the Electronic Equipment with the Panel Switch”, which introduces a method to adhere a cover plate made from a flexible insulated base plate, on whose under surface an adhesive is coated, to the upper surface of a baseplate, so as to maintain their respective moving contacts inside the through-holes on the flexible insulated baseplate, and the active moving contacts are moveable on the thin adhesive layer except for through-holes of the baseplate, taking advantage of adhering the thin adhesive layer to the base plate where the fixed contacts are corresponding to the moving contacts to realize an anti-dust function of the switch panel. Said invention adopts an anti-dust adhering method, but the panel switch of said invention is not suitable for a long time service, even losing the electric conductivity due to excessive dust stuck thereto.
Chinese Patent Application No. 201110027418.8 discloses a “Conductive Rubber Pill”. The conductive rubber pill contains a rubber base and a metal coating film which is on the surface of the rubber base. The metal coating film could be one layer or more layers, and the total thickness of the metal coating film is 0.05 μm-1 mm. The conductive rubber pills are columnar, with circular, oval or polygonous cross-sections whose diameters are 1-10 mm. The preparation method is as follows: firstly, make rubber sheets by press molding, injection molding or by calendar molding; Secondly, apply a metallic coating on the rubber sheet with a plating process; and then punch, shear cut or laser cut the sheet to obtain the pills. The metallic coatings or platings on conductive rubber pills described in this invention have good electric conductivity, but these pills have low overall mechanical strength, and the metallic coatings are usually thin. As switch contacts, they have a relatively short service life.
Chinese Patent Application No. 201110193369.5 provides a “Roughened Metal and Rubber Composite Conductive Pills”, which are made by bonding a metal layer and a rubber matrix, or by cutting after bonding. The metal surface is roughened, with pits, bumps, or both. The pits and bumps are on the external or internal surface of the metal layer, or on both surfaces. The pitting depth is less than the thickness of the metal layer, and the height of bumps is not less than 1/10 of the metal layer thickness. The metal layer material is a metal or an alloy, and the external surface of the metal layer can be plated with gold, silver, copper or nickel etc. the rubber matrix is silicone rubber or polyurethane rubber. Between the metal surface and the rubber matrix there may be a layer of adhesive, which is a kind of thermal cured adhesive or primer, or the same material as the rubber matrix. The metal layer can be coated with a coupling agent and other adhesion promoters. In said invention, the metal layer has high strength, stable electrical conductivity and high bonding strength, and the rubber matrix has high elasticity; when the roughened metal surface is plated with precious metals such as gold or silver, a larger surface area results in more precious metal consumption, as compared to the plating on a flat metal surface. This leads to a high cost, and thus the practical applications would be limited. Moreover, as the relationship between the electrical conductivity and the size and spacing of pits and bumps is unclear and undetermined, the direct use of this technology is impacted by some unknown technical issues.
Chinese Patent Application No. 2011100278634 discloses “A process to Partially Plate Gold on the Commemorative Coins”, introducing a decorative gold plating process and its product. This patent does not relate the effect of partial gold plating on the mechanical properties and electrical properties.